/Engine/Source/Runtime/Engine/Classes/GameFramework/PlayerController.h
Forces the streaming system to disregard the normal logic for the specified duration and instead always load all mip-levels for all textures used by the specified actor.
void ClientPrestreamTextures ( class [AActor](API\Runtime\Engine\GameFramework\AActor) * ForcedActor, float ForceDuration, bool bEnableStreaming, int32 CinematicTextureGroups )